Right from the beginning after fertilisation an animal's behaviour is regulated by hormones. A fertilised ova (zygote) sends out many different messages to alter the body for pregnancy. Most animals do not realise that there is actually one or moreababies on the way. Improved food intake and nest arrangement is part of the hormonal changes and if, say a cat, could speak and be asked why it is preparing a cozy corner in the bottom of the wardrobe it would have no idea. All the stages of birth or egg laying and incubating is all regulated by hormones.